The subject matter disclosed herein relates to turbines and, more particularly, to systems and devices for reducing intrusion losses in a working fluid flowpath during turbine operation.
Some power plant systems, for example certain nuclear, simple cycle and combined cycle power plant systems, employ turbines in their design and operation. Some of these turbines are driven by a flow of high temperature steam which is directed over and/or through a series of stages (e.g., alternating stationary and rotary airfoils/buckets/blades) within the turbine. As the main flow passes through the turbine, portions of the flow may leak from the main flowpath. This leakage flow may travel through the clearance formed between the tip of one of the blades and the turbine casing rather than traveling through the stage/airfoils. As this leakage flow travels through the turbine, it may randomly contact turbine surfaces (e.g., blade roots, the turbine casing, etc.) and be redirected out into the main flow at an angle substantially different (e.g., perpendicular) to a direction of the flowpath of the working fluid. As a result of variances in pressure, momentum, and direction of travel between the leakage flow and the working fluid flowpath, this reintroduction and random mixing of the leakage flow and working fluid flowpath may create intrusion losses, windage losses, and system inefficiencies.